Add-drop filter based on TiO2 coated shifted Bragg grating
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CitationPaul Somnath. Vartiainen Ismo. Roussey Matthieu. Saastamoinen Toni. Tervo Jani. Honkanen Seppo. Kuittinen Markku. (2016). Add-drop filter based on TiO2 coated shifted Bragg grating. OPTICS EXPRESS: THE INTERNATIONAL ELECTRONIC JOURNAL OF OPTICS, 24 (23) , 26901-26910. 10.1364/OE.24.026901.
We present a titanium dioxide coated shifted Bragg grating in a silicon-on-insulator platform enabling optical add-drop functionality. The device works on the basis of mode conversion due to shifted sidewall structure followed by mode splitting based on an asymmetric Y-coupler. We experimentally demonstrate the working principle of the device. A reflection bandwidth of 2.2 nm with 14 dB extinction ratio is obtained with a 300 μm long shifted Bragg grating. The performance of the device is also compared without the titanium dioxide coating. A scope of spectral tunability with titanium dioxide re-coating (0.8 nm per 1 nm re-coating) by atomic layer deposition is experimentally verified.